1. Field of the Invention
The invention relates to a multi-domain vertical alignment liquid crystal display panel, and more particularly, to a multi-domain vertical alignment liquid crystal display panel having common electrode and pixel electrode with jagged patterns.
2. Description of the Prior Art
Liquid crystal displays are commonly utilized in various electronic products including cell phones, PDAs, and notebook computers. As the market demand for large-scale display panels continues to increase, liquid crystal displays having advantages such as small size and light weight have become widely popular. In fact, LCDs are gradually replacing the conventional cathode ray tube (CRT) displays that had dominated the market for so many years. However, the viewing angle of the conventional liquid crystal displays is not sufficiently wide to ensure a high display quality, therefore, the development of liquid crystal displays is limited by this important factor. A multi-domain vertical alignment (MVA) display capable of orientating liquid crystals in various directions is therefore made to improve the problem of the previously described insufficient viewing angle of the conventional displays.
FIG. 1 is a perspective diagram illustrating a liquid crystal display panel according to the prior art. As shown in FIG. 1, the liquid crystal display panel 100 is a multi-domain vertical alignment liquid crystal display panel, in which the liquid crystal display panel 100 includes an upper substrate 102, a color filter layer 104, a common electrode 106, a plurality of liquid crystals 108, a pixel electrode 110, and a lower substrate 114. The common electrode 106 includes a plurality of protrusions 116 disposed thereon, and the pixel electrode 110 of each pixel includes a slit 118 positioned relatively between the protrusions 116. Due to a fringe field effect caused by the protrusions 116 and the slit 118, the liquid crystals 108 are able to align in different directions, specifically, thereby increasing the viewing angle of the liquid crystal display panel 100.
However, it is known that as the distance between the protrusions 116 and the slit 118 increases, the liquid crystals between the protrusions 116 and the slit 118 require more time for aligning as the adjacent liquid crystals tilt. The result increases the response time of the liquid crystals, and also results in a disclination phenomenon. Typically, the disclination phenomenon is caused by the weak fringe field effect exerted on the liquid crystals between the protrusions 116 and the slit 118, and the influence of the vertical electric field on the liquid crystals. Often this results in an uncontrollable alignment of the liquid crystals.
Another factor contributing to the disclination phenomenon involves an abrupt increase of high voltage. Preferably, the alignment of the liquid crystals between the protrusions 116 and the slit 118 are affected by the vertical electric field before being influenced by the tilting of the adjacent liquid crystals, in which the liquid crystals between the protrusions 116 and the slit 118 will tilt toward any direction as a result of the impact caused by the vertical electric field. Since the tilting direction of the liquid crystals is not controlled by the fringe field effect, the disclination phenomenon will result. Ultimately this produces gray spots or black spots, which can be observed under an optical microscope.
Essentially, liquid crystals tilting toward any direction that do not align according to a 45 degree angle with respect to an upper and lower polarizer of the display cause the gray spots and black spots. For example, this can happen when the adjacent liquid crystals induce the liquid crystals suffering from disclination to re-tilt back to a proper 45 degree angle with respect to the upper and lower polarizer. A significantly longer time is required to accomplish the needed correction and eventually this results in an increase in the response time. Moreover, when the adjacent liquid crystals fail to induce such said change on the liquid crystals suffering from disclination, the gray spots or the black spots will appear on the liquid crystals and the brightness of the liquid crystals will be significantly affected.
It is known that the driving of the multi-domain vertical alignment liquid crystal display involves a threshold voltage, such that when an external driving voltage applied on the display exceeds the threshold voltage, the disclination phenomenon described previously will take place. Hence, the conventional MVA displays must ensure that the driving voltage is maintained well below the threshold voltage, thereby reducing the overall response time of the display. Additionally, the gap between the protrusions and the slit must also be maintained under a certain distance to prevent the disclination phenomenon. By reducing the gap between the protrusions and the slit, the threshold voltage can be increased and the range of driving voltage being utilized can be further increased. However, as the gap between the protrusions and slit is reduced, the number of protrusions and slits within a pixel will also increase. Additionally, because the protrusions and slits are essentially non-display regions, the aperture ratio of the pixel region of the display will decrease and ultimately reduce the brightness of the liquid crystal display.
FIG. 2 is a perspective diagram illustrating another liquid crystal display panel according to the prior art. As shown in FIG. 2, the liquid crystal display panel 100 includes an upper substrate 202, a color filter layer 204, a common electrode 206, a plurality of liquid crystals 208, a pixel electrode 210, and a lower substrate 214. The common electrode 206 includes a plurality of protrusions 216. In contrast to the panel 100 described in FIG. 1, the pixel electrode 210 of the liquid crystal display panel 200 includes a plurality of jagged patterns 218 in the slit region and between the protrusions 216. The jagged patterns 218 allow the liquid crystals 218 to align in a specific manner and toward different directions, and also increase the fringe field of the slits and the protrusions. As a result, said jagged patterns 218 thereby improve the response time of the liquid crystals. Despite the fact that the gap between the protrusions and the slits can be increased, problems such as disclination of the liquid crystals continue to occur. Hence, the gap between the protrusions and the slits must be maintained below a certain value, thereby limiting the aperture ratio of the pixel region.
As mentioned previously, despite the fact that both of the liquid crystal panel 100 and 200 exhibit a wide viewing angle characteristic, the response time of the liquid crystals is still not fast enough, thereby resulting in problems, for example, such as shadowing. Additionally, disadvantages such as low aperture ratio and insufficient transmittance of the light of the display panels also significantly influence the performance of the liquid crystal display.